Circuit breakers having abutting arcing contacts are known and comprise a gastight case filled with a gas having good dielectric properties such as sulfur hexaflouride, and in which the arc is blasted by gas being compressed during an opening operation. In circuit breakers of this type, the gas is compressed before the arcing contacts separate (this is referred to as "precompression"); during this precompression stage, the main contacts of the circuit breaker are opened, which main contacts may be located outside the case; the drawback of the precompression stage is that it requires considerable drive energy and this detrimental to the cost of the apparatus.
An object of the present invention is to provide a circuit breaker having abutting arcing contacts for arc blasting but requiring only a small amount of drive energy.